A novel class of antagonists for metabotropic glutamate receptors, 7-(Hydroxyimino)cyclopropa[b]chromen-1a-carboxylates

7-(Hydroxyimino)cyclopropa[b]chromen-la-carboxylates (4a-c), highly potent antagonists for a phospholipase C-linked metabotropic glutamate receptor, mGluR1, were synthesized through cyclopropanation onto 4-oxo-4H-1-benzopyran-2-carboxylates (5a-c) utilizing dimethyloxosulfonium methylid followed by treatment with hydroxylamine.